backing-dev: ensure that a removed bdi no longer has super_block referencing it

[cascardo/linux.git] / mm / backing-dev.c

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3d3accb..1065b71 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -92,7 +92,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                   "BdiDirtyThresh:   %8lu kB\n"
                   "DirtyThresh:      %8lu kB\n"
                   "BackgroundThresh: %8lu kB\n"
-                  "WriteBack threads:%8lu\n"
+                  "WritebackThreads: %8lu\n"
                   "b_dirty:          %8lu\n"
                   "b_io:             %8lu\n"
                   "b_more_io:        %8lu\n"
@@ -610,6 +610,21 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
                kthread_stop(wb->task);
 }
 
+/*
+ * This bdi is going away now, make sure that no super_blocks point to it
+ */
+static void bdi_prune_sb(struct backing_dev_info *bdi)
+{
+       struct super_block *sb;
+
+       spin_lock(&sb_lock);
+       list_for_each_entry(sb, &super_blocks, s_list) {
+               if (sb->s_bdi == bdi)
+                       sb->s_bdi = NULL;
+       }
+       spin_unlock(&sb_lock);
+}
+
 void bdi_unregister(struct backing_dev_info *bdi)
 {
        if (bdi->dev) {
@@ -682,6 +697,7 @@ void bdi_destroy(struct backing_dev_info *bdi)
                spin_unlock(&inode_lock);
        }
 
+       bdi_prune_sb(bdi);
        bdi_unregister(bdi);
 
        for (i = 0; i < NR_BDI_STAT_ITEMS; i++)